1. Field of the Invention
The present invention relates to a dynamo electric machine and a method of manufacturing the same, and, in particular, relates to a dynamo electric machine which is suitable for size reduction and a method of manufacturing the same.
2. Conventional Art
As, for example, disclosed in JP-A-10-66314 (1998), JP-A-8-298756 (1996) and JP(PCT)-A-10-507057 (1998), a stator winding of a conventional dynamo electric machine is constituted in such a manner that a plurality of unit windings are manufactured in advance by molding a winding conductor wound in a plurality of times in a predetermined shape (for example, a hexagonal shape) and are disposed into a plurality of slots in a stator core so that each of the unit windings crosses over the plurality of slots. Further, as disclosed in JP-A-6-209535 (1994), each of a plurality of unit windings which constitutes the stator winding is constituted by two parts one as an in-slot coil and the other as an inter slot crossover coil.
The above referred to crossing over amount of the unit winding is determined based on the number of poles of the stator, therefore, the length of the end section of the unit winding is determined by the magnitude of the crossing over amount. When the number of poles of the stator is large, the amount of crossing over of the unit winding generally decreases, therefore, the length of the end section of the unit winding is shortened in comparison with a stator having a small number of poles. Further, the length of the end section of the unit winding can be shortened by a certain degree by improving the shape of a portion corresponding to the end section of the unit winding of a winding frame used when winding the winding conductor.
However, when the length of the end section of the unit winding is greatly shortened, the disposing work of the winding conductor into slots of the stator core is disturbed. Therefore, the following measure is conceived, in that at the time of disposing the unit winding while limiting the length shortening of the end section of the unit winding so as not to disturb the disposing work, the unit winding are disposed into the slots of the stator core, and after completing the disposing of all of the unit windings the respective sections of the unit windings are forcedly shaped to shorten the same.
However, such manufacturing method requires a large mechanical force to shape the end sections of the unit windings, further, when shaping the end sections of the unit windings, such as an insulating member inserted in the slots of the stator core and an enamel insulative coating applied over the surface of the winding conductor may be damaged which likely causes to lower the break down voltage of the stator and to decrease the performance of the dynamo electric machine concerned. Still further, the amount of the forced shortening of the end sections of the unit winding is limited, therefore, it is impossible to expect a significant shortening of the end section of the unit winding with such measure.
With regard to the above problem, in the former prior art referred to above, it is impossible to shorten the length of the end section of the unit winding while preventing disturbance at the time of disposing work of the winding conductor, because the unit windings are shaped in advance. Further, the latter prior art referred to above takes no account of the significant shortening of the length of the end sections by shaping the end sections of the unit windings.